C语言字符串操作常用库函数***********************************************************************************函数名: strrchr 功 能: 在串中查找指定字符的最后一个出现 用 法: char *strrchr(char *str, char c);举例：view plaincopy to clipboardprint?char fullname="./lib/lib1.so";char *ptr;ptr = strrchr(fullname,'/');printf("filename is %s",++ptr);//运行结果：filename is lib1.so***********************************************************************************函数名: strchr 功 能: 在串中查找指定字符的第一个出现 用 法: char *strchr(char *str, char c);举例：view plaincopy to clipboardprint?char fullname="./lib/lib1.so";char *ptr;ptr = strrchr(fullname,'.');printf("after strchr() is %s",++ptr);//运行结果：after strchr() is /lib/lib1.so***********************************************************************************函数名: strtok 功 能: 在串中查找指定字符的第一个出现 用 法: char *strtok(char *s, char *delim);说明：1.strtok函数的实质上的处理是，strtok在s中查找包含在delim中的字符并用NULL(’\0′)来替换,直到找遍整个字符串。这句话有两层含义：（1）每次调用strtok函数只能获得一个分割单位。（2）要获得所有的分割单元必须反复调用strtok函数。2.strtok函数以后的调用时的需用NULL来替换s.3.形参s(要分割的字符串)对应的变量应用char s[]=”….”形式，而不能用char *s=”….”形式。举例：view plaincopy to clipboardprint?void main(){char buf[]=”Golden Global View”;char* token = strtok( buf, ” “);while( token != NULL ){printf( ”%s “, token );token = strtok( NULL, ” “);}return 0;}/*其结果为： GoldenGlobalView*/***********************************************************************************函数名：strncpy功能：把src所指由NULL结束的字符串的前n个字节复制到dest所指的数组中用法：char *strncpy(char *dest, char *src, int n);说明：如果src的前n个字节不含NULL字符，则结果不会以NULL字符结束。 如果src的长度小于n个字节，则以NULL填充dest直到复制完n个字节。 src和dest所指内存区域不可以重叠且dest必须有足够的空间来容纳src的字符串。 返回指向dest的指针。举例：view plaincopy to clipboardprint? #include #include main(){char buf[4];char *s="abcdefg";strncpy(buf,s,4);printf("%s\n",buf);return 0;}/*运行结果：abcd*/***********************************************************************************函数名: stpcpy功 能: 拷贝一个字符串到另一个用 法: char *stpcpy(char *destin, char *source);举例：view plaincopy to clipboardprint?#include #include int main(void){char string[10];char *str1 = "abcdefghi";stpcpy(string, str1);printf("%s\n", string);return 0;}/*运行结果abcdefghi*/***********************************************************************************函数名: strcat功 能: 字符串拼接函数用 法: char *strcat(char *destin, char *source);举例：view plaincopy to clipboardprint?#include #include int main(void){char destination[25];char *blank = " ", *c = "C++", *Borland = "Borland";strcpy(destination, Borland);strcat(destination, blank);strcat(destination, c);printf("%s\n", destination);return 0;}/*运行结果：Borland C++*/***********************************************************************************函数名: strcmp功 能: 串比较用 法: int strcmp(char *str1, char *str2);看Asic码，str1>str2，返回值 > 0；两串相等，返回0举例：view plaincopy to clipboardprint?#include #include int main(void){char *buf1 = "aaa", *buf2 = "bbb"；int ptr;ptr = strcmp(buf2, buf1);if (ptr > 0)printf("buffer 2 is greater than buffer 1\n");else if(ptr < 0)printf("buffer 2 is less than buffer 1\n");elseprintf("buffer 2 is equal with buffer 1\n");return 0;}/*运行结果：buffer 2 is greater than buffer 1*/***********************************************************************************函数名: strncmpi功 能: 将一个串中的一部分与另一个串比较, 不管大小写用 法: int strncmpi(char *str1, char *str2, unsigned maxlen);举例：view plaincopy to clipboardprint?#include #include int main(void){char *buf1 = "BBB", *buf2 = "bbb";int ptr;ptr = strcmpi(buf2, buf1);if (ptr > 0)printf("buffer 2 is greater than buffer 1\n");if (ptr < 0)printf("buffer 2 is less than buffer 1\n");if (ptr == 0)printf("buffer 2 equals buffer 1\n");return 0;}***********************************************************************************函数名: strcspn功 能: 在串中查找第一个给定字符集内容的段用 法: int strcspn(char *str1, char *str2);举例：view plaincopy to clipboardprint?#include #include #include int main(void){char *string1 = "1234567890";char *string2 = "747DC8";int length;length = strcspn(string1, string2);printf("Character where strings intersect is at position %d\n", length);return 0;}***********************************************************************************函数名: strdup功 能: 将串拷贝到新建的位置处用 法: char *strdup(char *str);举例：view plaincopy to clipboardprint?#include #include #include int main(void){char *dup_str, *string = "abcde";dup_str = strdup(string);printf("%s\n", dup_str);free(dup_str);return 0;}***********************************************************************************函数名: stricmp功 能: 以大小写不敏感方式比较两个串用 法: int stricmp(char *str1, char *str2);举例：view plaincopy to clipboardprint?#include #include int main(void){char *buf1 = "BBB", *buf2 = "bbb";int ptr;ptr = stricmp(buf2, buf1);if (ptr > 0)printf("buffer 2 is greater than buffer 1\n");if (ptr < 0)printf("buffer 2 is less than buffer 1\n");if (ptr == 0)printf("buffer 2 equals buffer 1\n");return 0;}***********************************************************************************函数名: strerror功 能: 返回指向错误信息字符串的指针用 法: char *strerror(int errnum);举例：view plaincopy to clipboardprint?#include #include int main(void){char *buffer;buffer = strerror(errno);printf("Error: %s\n", buffer);return 0;}***********************************************************************************函数名: strncmp功 能: 串比较用 法: int strncmp(char *str1, char *str2, int maxlen);举例：view plaincopy to clipboardprint?#include #include int main(void){char *buf1 = "aaabbb", *buf2 = "bbbccc", *buf3 = "ccc";int ptr;ptr = strncmp(buf2,buf1,3);if (ptr > 0)printf("buffer 2 is greater than buffer 1\n");elseprintf("buffer 2 is less than buffer 1\n");ptr = strncmp(buf2,buf3,3);if (ptr > 0)printf("buffer 2 is greater than buffer 3\n");elseprintf("buffer 2 is less than buffer 3\n");return(0);}***********************************************************************************函数名: strncmpi功 能: 把串中的一部分与另一串中的一部分比较, 不管大小写用 法: int strncmpi(char *str1, char *str2, int len);举例：view plaincopy to clipboardprint?#include #include int main(void){char *buf1 = "BBBccc", *buf2 = "bbbccc";int ptr;ptr = strncmpi(buf2,buf1,3);if (ptr > 0)printf("buffer 2 is greater than buffer 1\n");if (ptr < 0)printf("buffer 2 is less than buffer 1\n");if (ptr == 0)printf("buffer 2 equals buffer 1\n");return 0;}***********************************************************************************函数名: strnset功 能: 将一个串中的所有字符都设为指定字符用 法: char *strnset(char *str, char ch, unsigned n);举例：view plaincopy to clipboardprint?#include #include int main(void){char *string = "abcdefghijklmnopqrstuvwxyz";char letter = 'x';printf("string before strnset: %s\n", string);strnset(string, letter, 13);printf("string after strnset: %s\n", string);return 0;}***********************************************************************************函数名: strpbrk功 能: 在串中查找给定字符集中的字符用 法: char *strpbrk(char *str1, char *str2);举例：view plaincopy to clipboardprint?#include #include int main(void){char *string1 = "abcdefghijklmnopqrstuvwxyz";char *string2 = "onm";char *ptr;ptr = strpbrk(string1, string2);if (ptr)printf("strpbrk found first character: %c\n", *ptr);elseprintf("strpbrk didn't find character in set\n");return 0;}***********************************************************************************函数名: strrev功 能: 串倒转用 法: char *strrev(char *str);举例：view plaincopy to clipboardprint?#include #include int main(void){char *forward = "string";printf("Before strrev(): %s\n", forward);strrev(forward);printf("After strrev(): %s\n", forward);return 0;}/*运行结果：Before strrev(): stringAfter strrev(): gnirts*/***********************************************************************************函数名: strstr功 能: 在串中查找指定字符串的第一次出现用 法: char *strstr(char *str1, char *str2);举例：view plaincopy to clipboardprint?#include #include int main(void){char *str1 = "Borland International", *str2 = "nation", *ptr;ptr = strstr(str1, str2);printf("The substring is: %s\n", ptr);return 0;}***********************************************************************************函数名: strtod功 能: 将字符串转换为double型值用 法: double strtod(char *str, char **endptr);举例：view plaincopy to clipboardprint?#include #include int main(void){char input[80], *endptr;double value;printf("Enter a floating point number:");gets(input);value = strtod(input, &endptr);printf("The string is %s the number is %lf\n", input, value);return 0;}***********************************************************************************函数名: strtol功 能: 将串转换为长整数用 法: long strtol(char *str, char **endptr, int base);举例：view plaincopy to clipboardprint?#include #include int main(void){char *string = "87654321", *endptr;long lnumber;/* strtol converts string to long integer */lnumber = strtol(string, &endptr, 10);printf("string = %s long = %ld\n", string, lnumber);return 0;}***********************************************************************************函数名: strupr功 能: 将串中的小写字母转换为大写字母用 法: char *strupr(char *str);举例：view plaincopy to clipboardprint?#include #include int main(void){char *string = "abcdefghijklmnopqrstuvwxyz", *ptr;/* converts string to upper case characters */ptr = strupr(string);printf("%s\n", ptr);return 0;}